If possible add more logging or increase logging levels. Not sure what
language / runtime you're using, but you might be able to add an exit hook
or some code that is guaranteed to run before your app exits and use that
to dump more info.

If CF were shutting down your app for some reason, you would see a SIGTERM
sent followed by a SIGKILL roughly 10 seconds later (if your app doesn't
gracefully exit first). I don't think that's what is happening here, but
you could catch the SIGTERM and log a message to check. CF would really
only do this if the cell that your app is running on were being shut off
(like during an upgrade). Then it would restart your app automatically on
another cell.

The other case could be that you're exceeding your MEMORY_LIMIT. I don't
think that's happening as I believe Diego logs something that specifically
says when you run out of memory (like `Exited with status 255 (out of
memory)`).

Dan